Electric Potential conducting shell

[suspenc3]

Homework Statement

A thin, spherical, conducting shell of radius R is mounted on an isolating support and charged to a potential of $$-V$$. An electron is then fired from point $$P$$ at a distance $$r$$ from the center of the shell. $$(r>>R)$$ with an initial speed $$v_0$$ and directly towards the shell's center. What value of $$v_0$$ is needed for the electron to just reach the shell before reversing direction?

Homework Equations

$$\Delta u = \frac{1}{2}mv_0^2$$

The Attempt at a Solution

$$v_0=\sqrt{\frac{2 \Delta u}{m}}$$

Im not sure if this is what I should do, if so, how can I get something for $$\Delta u$$

 

[robphy]

What is the PHYSICS underlying the "relevant equation"?
What does $$\Delta u$$ mean? and how is it related to the "Electric Potential"?

 

[Nacer]

What is the PHYSICS underlying the "relevant equation"?

Conservation of Energy Kinetic Energy + Potential Energy = Constant.

What does Delta u mean? and how is it related to the "Electric Potential"?

Delta U = changes in Potential Energy
= e*V

Regards,

Nacer.

 

[suspenc3]

does "V" have a value?